I chose the early May time frame to avoid the large summer crowds in Yellowstone. I arrived there on10 May, and left on 12 May, the day the Southern access road to the park opened. I thought the weather would be cold so Ly and I brought plenty of warm clothes. The 3 days we spent there was perfect weather. It was bright sunshine and short sleeve weather.
We Spent the 1st night in Reno, NV. The 2nd night in Twin Falls Idaho. 3 days and 2 nights in West Yellowstone (just outside the park). We had a great time exploring the park. We spent 1 night each in Provo, Utah, and Las Vegas, NV on the return trip. 2,608 miles total, and a great trip.